What is Error 5.1.1?

Error 5.1.1 occurs when an email is sent to a recipient whose email address is invalid or does not exist on the receiving server. Common causes of this error include:

  • The recipient's email address has a typo or formatting error.
  • The email account has been deactivated, deleted, or does not exist.
  • The recipient's domain is incorrect or not properly configured.

This error typically results in a "bounce" email being returned to the sender with the error message.

How to Fix Error 5.1.1?

Follow these steps to resolve Error 5.1.1:

  1. Verify the Recipient's Email Address:
    • Double-check the recipient's email address for typos or missing characters.
    • Ensure the domain portion of the email address (e.g., @example.com) is correct and active.
  2. Confirm the Email Account Exists:
    • Contact the recipient using an alternative method (e.g., phone, text) to confirm their email account is active.
    • If the account has been deactivated, request a new email address from the recipient.
  3. Update Your Contact List:
    • Remove invalid or outdated email addresses from your contact list.
    • Use an email validation tool to identify invalid addresses before sending emails.
  4. Retry Sending the Email:
    • Once the recipient's address has been corrected or updated, resend the email.

Preventing Error 5.1.1 in the Future

  • Regularly clean and update your email lists to remove inactive or invalid addresses.
  • Implement a double opt-in process to ensure recipients provide valid email addresses.
  • Use an email validation service to verify the accuracy of email addresses before sending campaigns.
  • Monitor email bounce reports to identify and address recurring issues.

Error 5.1.1 can often be avoided by maintaining a clean and accurate contact list. If the issue persists despite these steps, contact your email service provider for further assistance.

 

List of Common SMTP Errors

 

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